<template>
  <view>
    <!-- 顶部搜索框 -->
    <my-search @click="gotoSearch"></my-search>
    <view class="scroll-view-container">
      <!-- 左侧的滚动视图区域 -->
      <scroll-view class="left-scroll-view" direction="vertical" style="{height: wh +'px';}">
        <block v-for="(item, i) in cateList" :key="i">
          <view :class="['left-scroll-view-item', i===active ? 'active' : '']" @click="activeChanged(i)">
            {{ item.cat_name }}
          </view>
        </block>
      </scroll-view>
      <!-- 右侧的滚动视图区域 -->
      <scroll-view class="right-scroll-view" direction="vertical" style="{height: wh +'px';}" :scroll-top="scrollTop">
        <view class="cate-lv2" v-for="(item2,i2) in cateLevel2" :key="i2">
          <view class="cate-lv2-title"> {{item2.cat_name}}</view>
          <!-- 动态渲染三级分类的列表数据 -->
          <view class="cate-lv3-list">
            <view class="cate-lv3-item" v-for="(item3,i3) in item2.children" :key="i3" @click="gotoGoodsList(item3)">
              <image :src="item3.cat_icon" class="cate-lv3-img"></image>
              <text>{{item3.cat_name}}</text>
            </view>
          </view>
        </view>
      </scroll-view>
    </view>
  </view>
</template>

<script>
  export default {
    data() {
      return {
        // 窗口的可用高度 = 屏幕高度 - navigationBar高度 - tabBar 高度
        wh: 100,
        //分类数据列表
        cateList: [],
        //被点击的左侧分类的索引
        active: 0,
        //二级分类列表
        cateLevel2: [],
        //滚动条距离顶部的位置
        scrollTop: 0,

      };
    },

    onLoad() {
      // 获取当前系统的信息
      const sysInfo = uni.getSystemInfoSync()
      // 为窗口可用高度赋值
      this.wh = sysInfo.windowHeight - 50
    },

    methods: {
      // 获取分类数据列表
      async getCateList() {
        const {
          data: res
        } = await uni.$http.get('/api/public/v1/categories')
        if (res.meta.status !== 200) return uni.$showMsg()
        this.cateList = res.message
        this.cateLevel2 = res.message[0].children
      },

      // 获取二级分类列表数据
      async getCateLevel2List(cat_id) {
        const {
          data: res
        } = await uni.$http.get('/api/public/v1/categories/' + cat_id + '/subcategories')
        if (res.meta.status !== 200) return uni.$showMsg()
        this.cateLevel2List = res.message
      },

      // 修改被点击的左侧分类的索引
      activeChanged(i) {
        this.active = i
        //根据被点击的左侧分类的索引，为二级分类列表重新赋值
        this.cateLevel2 = this.cateList[i].children
        // 让srollTop的值在0和1之间切换
        this.scrollTop = this.scrollTop ? 0 : 1
      },

      // 跳转到商品列表页面
      gotoGoodsList(item3) {
        uni.navigateTo({
          url: '/subpkg/goods_list/goods_list?cid=' + item3.cat_id
        })
      },

      // 跳转到搜索页面
      gotoSearch() {
        uni.navigateTo({
          url: '/subpkg/search/search'
        })
      },
    }
  }
</script>

<style lang="scss">
  .scroll-view-container {
    display: flex;

    .left-scroll-view {
      width: 120rpx;

      .left-scroll-view-item {
        line-height: 60rpx;
        text-align: center;
        background-color: #f7f7f7;
        font-size: 12px;

        &.active {
          background-color: #ffffff;
          position: relative;

          //渲染左侧选中分类的指示边框
          &::before {
            content: '';
            display: block;
            width: 3px;
            height: 30px;
            background-color: #c00000;
            position: absolute;
            left: 0;
            top: 50%;
            transform: translateY(-50%);
          }
        }
      }
    }

    .right-scroll-view {
      .cate-lv2-title {
        font-size: 12px;
        font-weight: bold;
        text-align: center;
        padding: 15px 0;
      }

      .cate-lv3-list {
        display: flex;
        flex-wrap: wrap;

        .cate-lv3-item {
          width: 33.33%;
          display: flex;
          flex-direction: column;
          align-items: center;
          justify-content: center;
          margin-bottom: 10px;
          font-size: 12px;

          .cate-lv3-img {
            width: 60px;
            height: 60px;
          }
        }
      }
    }
  }
</style>